Treatment of chrome leather



Patented Dec. 17, 1940 UNITED STATES PATENT OFFICE 2,225,083 TREATMENT or CHROME LEATHER tion of Delaware No Drawing. Application October 22, 1937, Se-

rial No. 170,390.

In Germany October 31, 1936 4 Claims. 149-6) The present invention relates to a new treatment of leather tanned with chrome tanning agents for the purpose of deacidifying it.

We have found that deacidifying can be advan- 5 tageously carried out with basic-reacting salts, in particular alkali or alkaline earth metal salts or quaternary ammonium salts, of weak nitrogenous organic polycarboxylic acids which have the property of so changing chromium hydroxide free from electrolytes in neutral aqueous solu-' tion that by the subsequent addition of acid or substantive dyestufis, which otherwise would form diflicultly soluble compounds therewith, no

formation of difilcultly soluble compounds is caused.

Suitable salts are for example alkaline reacting alkali and alkaline earth metal salts, as well as quaternary ammonium salts of weak nitrogenous organic polycarboxylic acids, such as triglycolamic and aspartic acid.

The process, which may be used for leather which has been tanned with chrome tanning agents alone or with the co-employment of other tanning agents, offers the advantage that by dyeing the leather, very uniform dyeings are obtained.

The said deacidifying agents may be used as such, in admixture with each other, or in conjunction with known neutralizing agents or substances which favor the homogeneity of the dyeing of the leather. The deacidification may also be carried out simultaneously with the dyeing;

Example 100 parts of shaved chrome leather are treated Instead of the above mentioned deacidifying agents the salts of beta-nitrophthalic acid and aspartic acid may be employed.

What we claim is:

1. The process of deacidifying a leather tanned while using a chrome tanning agent which comprisestreating the said leather with a salt selected from the alkali metal, alkaline earth meta1 and quaternary ammonium salts of triglycolamic acid.

2. The process of deacidifying a leather tanned while using a chrome tanning agent which comprises treating the said leather with a basic-reacting salt of a weak organic nitrogenous polycarboxylic acid selected from the group consisting of triglycolamic acid and aspartic acid which salt has the property of so changing chromium hydroxide free from electrolytes in neutral aqueous solutions that by the subsequent addition of an acid dyestufi which otherwise would form a difiicultly soluble compound therewith, formation of a diificultly soluble compound is avoided.

3. The process of deacidifying a leather tanned while using a chrome tanning agent which comprises treating the said leather with a basic reacting alkali salt of a weak organic nitrogenous polycarboxylic acid selected from the group consisting of triglycolamic acid and aspartic acid which salt has the property of so changing chromium hydroxide free from electrolytes in neutral aqueous solutions that by the subsequent addition of an acid dyestuif which otherwise would form a diflicultly soluble compound therewith, formation of a difficultly soluble compound is avoided.

4. The process of deacidifying a leather tanned while using a chrome tanning agent which comprises treating the said leather with a basic-reacting salt selected from the class consisting of the alkali metal, alkaline earth metal and quaternary ammonium salts of organic nitrogenous polycarboxylic acids selected from the group consisting of triglycolamic acid and aspartic acid.

GERHARD o'rro. EUGEN HAMENDOERFER. 

